UDF? ISO 9660?

[trav]

Whats the difference between the two?

[query]

ISO 9660 is the High Sierra format - an almost-universal CD-ROM/CD-R specification set.

UDF refers to packet-written CD-RW discs.  This is not universal - most systems will not read a UDF-written CD-RW without a special driver.  Windows XP is the only version of Windows that can deal with packet-written discs without a driver.